This invention relates to cetane-enhancing additives for hydrocarbon fuels used in internal combustion engines and methods for preparing same.
Various cetane-enhancing compounds have been used as additives for improving the combustion efficiency of hydrocarbon fuels, such as diesel fuel, used in internal combustion engines. Three-tert-butyl-3-hydroxy-2,2,5,5-tetramethyl-4-hexano ne is a known compound. However, to the best of applicant's knowledge, neither it nor analogs thereof have been used as cetane-enhancing additive for improving the combustion efficiency of hydrocarbon fuels used in internal combustion engines. Methods for preparing the above compound are disclosed by F. J. Abruscato and T. T. Tidwell, J. Org Chem, 37, 4151-4156 (1972). These methods involve the addition of tert-butyllithium to pivalil or to di-tert-butylacetyl chloride. Both of the latter compounds are difficult to prepare. Consequently, these methods make the resulting product too costly for wide use as a cetane-enhancing additive for diesel fuels and the like.